Cover lock and extractor control



July 27, 1943. o. w. JOHNSON 2,325,406

COVER LOCK AND EXTRACTOR CONTROL Filed July 12, 1941 4 Sheets-Sheet l INVENTOR OSCAR W JOHNSON BY fTTORNEYs 4 Sheets-Sheet 2 O. W. JOHNSON COVER LOCK AND EXTRACTOR CONTROL Filed July 12, 1941 July 27, 1943.

INVENTOR BY OSCAR W. JOHNSON M ATTORNEYS July 27, 1943. o. w. JOHNSON 2,325,405

COVER LOCK AND EXTRACTOR CONTROL Filed July 12, 1941 4 Sheets-Sheet 3 FlG.-7

r i IZO O kl 7 I22 p32 12a z l3l FIG-5 INVENTOR Y OSCAR W. JOHNSON ATTORNEYS y 1943- 0. w. JOHNSON 2,325,406

COVER LOCK AND EXTRACTOR CONTROL Filed July 12, 1941 4 sheets-sheet 4 INVENTOR OSCAR W. JOHNSON Y Patented July 27, 1943 Oscar W. Johnson,

Rochester, N. Y., assignor to The American Laundry Machinery Company,

N orwood, Ohio, a

Application July 12,

13 Claims.

to centrifugal extractors such as are used, for example, for removing moisture from articles of clothing or textile fabin laundries, dry cleaning establishments,

The invention relates effected by the application of conventional braking means in conjunction with interruption of the power. The present invention is directed to the provision of means for insuring safe operation of extractors of this type, and is specifically directed to improved cover locking and clamping mechanisms, operatively associated with the aforementioned power means and braking means, whereby application of power to the work container is impossible, not only while the cover is in open position, but even, though closed, while securing means are detached, and further whereby opening of said cover is impossible so long In the drawings ing a part of this specification,

Fig. 1 is a side elevation of the extractor showing generally the location of the lock and-the automatic brake and control mechanism.

Fig. 3 is a side elevation of Fig. 2, the side of the casing thereof being broken away.

Fig. 4 is an enlarged fragmental sectional view taken on the line 4-4 of Fig. 2.

Fig. 5 is a fragmental view of the brake control mechanism in the extractor idle position, the cover being open and the brake released.

Fig. 6 nism in the extractor running position, the cover being closed and the brake released.

Fig. 7 is a plan view of a part of the extractor corporation of Ohio 1941, Serial No. 402,136

view of the brake mechanism looking in the direction of the arrows 8-8 of Fig. 1. Fig. 9 is a detail sectional view taken on the line 9-9 of Fig. 8.

Fig. 10 is a diagram of the electrical circuits. The extractor shown in the drawings is a conventional form comprising a curb IS, the base of which supports bearings, not shown,

upper end of the spindle is secured a basket [6, indicated in dotted lines, and to the lower end a combination brake drum and pulley H. The pulley is connected by belts I 8 to IS, the pulley posts are fixed to abase 24.

The curb is provided from a aft 26.

cover 25 fixed to This shaft is mounted in bearings position as shown in Fig. 7, dash-dot lines. An arm 28 is provided on the cover. Connected to the end of this arm is a chain or cable 29 which is retriever pulley 30.

The bearing bracket is provided with a pair of arms 3| provided with bumper springs 32 as shown, and to thereby provide a means of preventing noise and rattle during operation of the machine.

secured to the cover as shown in Fig. 4.

As will appear from the following description the cover is held in closed position by a lock heretofore been known.

and the armature and enough to bias the lock lever 38 in a clockwise v 2 trifugal mercury switch, mounted on the rotatable container, which makes contact only when at rest. Operation of the push button while the device is in operation accordingly has no effect on the cover lock, although, as will later appear, it does stop the rotation of the container by reason of other associated electrical circuits.

The cover is further secured by a manually operatable securing device, with which is associated a switch member in series circuit with the electrical leads to the motor which drives the rotatable container. when this securing device is in the idle position, whether the cover is open or closed, the said switch is open and the motor cannot be started. When the cover is closed and the securing device is in the cover-securing position, the said switch is closed and the motor can be started. Under such conditions, as will appear. the cover lock cannot be released, this being possible only when the securing device is moved to inoperative position. The motor circuits, therefore, are actively associated with the securing device, and not with the cover look, as has The construction and operation of the cover locking and securing devices, and their respective associated mechanical and electrical elements are now described.

The cover lock, generally designated 35, comprises a casing fixed to the side of the curb opposite the cover bearing bracket. In the casing, supported freely for rotative'movement, is a shaft 31 to which is pinned a lock lever 38 supporting a lock pin 39. This pin is adapted to cooperate with a lock finger 40 secured to the cover arm 4|. The shaft 31 also has fixed to it a lever 42; This lever is connected by a link 43 to a lever 44 which is pinned to the shaft 45. The shaft 45 also has pinned to it another lever 48 which is connected by a link 41 to the armature of a solenoid 48.

With the solenoid in deenergized condition, the weight of these parts, including the link 43 the connected levers, is

direction, isin the closed position, lock pin to normally engage in locking relation with the lock finger 40. When the solenoid is energized, the leverage system is rotated counterclockwise thereby removing the lock pin from locking relation with the finger 48.

The locking mechanism also includes a clamping means 49. This comprises a bolt 50 which is fixed to a shaft supported by bearings in the casing. The upper end of this bolt is threaded as shown at 52 and is adapted to receive a wing nut 53. When the bolt is swung from the open position, as shown in Fig. 1, to the clamping position, as shown in Fig. 4, it engages in a slot 54 in the cover arm 4 I. Then when the wing nut is turned down, the shoulder thereof engages the top of the cover arm over the slot and securely clamps the cover in a closed position as governed by the centering post 34 and pilot member 35. In this position, the cushion ring 33 engages the curb IS.

The right end of the shaft 5|, as viewed in Figs, 2 andgi, has a projecting pin 88 mounted eccentrically to the shaft center. When the clamping bolt is moved to the clamping position, this pin rotates and comes to a position shown in Fig. 4 just contacting a lateral branch arm SI of the lever 38'. This provides assurance that the lock pin 39, when once in looking engagement with the finger,.will remain until the clamping as seen in Fig. 4, and when the cover as shown, to cause the bolt is removed and prevents any possibility of the lock pin being forced out of locking engagement.

The shaft 5| has a cam 62 fixed to it. This cam is arranged to actuate a lever 83 pivotally mounted in a bracket at 64. The lower branch 85 of the-lever is adapted to actuate a switch 68. When the clamping bolt is in open position, as shown in Fig. 3, the cam 62 is in actuating position, relative to the lever '63, which through its branch 85, has depressed the switch to open circuit position. When the bolt is moved to the clamping position, the cam is out of operating engagement with the lever and the switch is permitted to close.

The upper end of the clamping bolt is provided with a collar 61. This is provided to limit the opening movement of the wing nut. It is provided with a depending lug 68 which engages with a corresponding lug 39 on the wing nut'which provides a stop but prevents a wedging action of the nut against the collar in the upper position.

I have provided, and will describe, braking means normally urged to applied position by a spring, but maintainable in released position by a latch. In order to permit brake application, the latch is tripped by a solenoid controlled by a timer device. The timer operation simultaneously opens a switch in the motor circuit thereby deenergizing the motor. The construction and operation of the brake mechanism and associated mechanical and electrical elements are now described.

The brake is the contracting band type. The

" band 15 is supported in alignment with the drum by three supporting blocks 16 spaced around the drum as indicated in Fig. 8. One end of the band 11 is fixed to a block 18 which in turn is secured to the bottom face of the curb as indicated in Fig. 1. To the block is secured an angle member 19. The block 18 and angle 19 constitute an anchorage. The depending branch of angle 19 is slotted to receive a rod 8|. One end of this rod is connected to a lever 82, see Figs. 8 and 9. The lever is freely mounted on a stud 83 secured to the curb. A lug 84 is provided on the hub of the lever 82 and this engages with a screw 85 threaded in a branch member 86 of a. lever 81. The lever 81 is connected at its end to the other end of the brake band 15 by a pin 10. This lever 81 is provided with an arcuate slot 38 and through this slot extends a stud 89 which is threaded into a branch 1| of the lever 82. Normally this stud is turned up to tightly secure. the levers 82 and 81 together for movement as an integral part. The screw 85 provides adjustment for the initial brake band setting and to compensate for wear of the band. When it is desired to make an adjustment of the band, the stud 89 is loosened and the screw 85 turned to produce the proper setting and the stud 89 is again tightened.

The other end of the rod 8| is pivotally connected to a bell crank 82 pivotally mounted in a bracket 93 as shown in Figs. 1 and 8. The other branch of the bell crank is pivotally connected to a rod 94 which extends upwardly into a housing 95 and is therein associated with control mechanism to be later described.

Interposed between the angle member 19 and a nut96 on the rod BI is a spring 91. With the brake in off position, this spring is in a an adjustable screw As before stated, the rod 94 extends upwar ly into the housing 95. As shown in Fig. 5, this 'rod inside of the housing is provided with a collar 98 which has a finger 99 which engages in a notch in a. latch I which is pivotally This latch is held normally in the latching position by a blocking arm I02, as shown in Fig. 5. The arm is pivotally mounted at I03 and intermediate its pivotal and free ends it is connected to the armature of a solenoid I04. .In the latched position of the rod 94 the brake has been released and the spring 91 has been compressed. When the solenoid I04 is energized, raising the blocking arm I02 to the dash-dot position of Fig. 6, the blocking effect on the latch is removed and the rod is free to move upwardly under the influence of the stored energy in the spring 91 so as to apply the brake. It will be noted that the pivotal point IOI of the latch is oil center, relative to the notch, so that the holding effect is removed when the locking arm is removed. Means are also provided to raise the blocking arm I02 manually. This comprises a branch arm I05 provided with I06 which is adapted to contact a push button I01 mounted in a side wall of the housing. Manually depressing this button produces the same effect on the arm as energization of the solenoid.

Numeral IIO designates generally an oil check. The piston III of this check is II3 into which works a plunger II4. A screw H5 is provided for plunger adjustment. A ball check relief valve H6 permits unrestricted flow of oil in the return movement of the piston.

The operation of this mechanism is as follows:

the rod 94 by spring 91 is under the control of the plunger valve. This mechanism may be set for a given braking time in the following manner.

With the screw II5 set at the upper limit, the adjusting nut 96 on the rod 8I is set so that empty, will stop in Now assume that it is desired, under operation, to stop the basket in 80 seconds. The adjusting screw II 5 is screwed down positioning the plunger II4 relative to the orifice II3 so that the basket will stop in 80 seconds. It will be understood that the orifice H3 is just slightly larger in diameter than the plunger H4.

The upper end of the rod 94 is guided by a member H8. Above the rod 94 in the housing 95 there is another rod I 20 guided for vertical movement by guides I2I and I22. This rod extends upwardly and is connected by a link I23 to a lever I24 fixed to a shaft I25 which is connected by universal coupling to the cover shaft 26. When the cover is in the closed position, this rod I20 is in the position of Fig. 6 and when the cover is opened, it is moved downwardly to the position of Fig. 5. Assuming that the brake has just been applied to stop the extractor,

' switches 68, I26

the rod 94 will be in its uppermost position, not shown. When the cover is thereupon moved to the open position causing the rod I 20 to be lowered, it engages the rod 94 in end to end relationship, returning it to its lower latched position and resetting the brake for the next operation.

Numeral I26 designates a normally closed limit switch.

rod 94 when it is moved upwardly upon application of the brake. In this case, the rod 94 engages the roller and rotates the arm I 21 clockwise which depresses the stem of the switch. The actuation on the stem is through a spring I3I. The arm 128 is pivoted at I32. When the cover is opened and the rod I20 is lowered, the arm I28 is rotated This is m0- tating switch.

The controlling apparatus comprises the and I34. The switch 66 is associated with the clamping bolt in the cover lock housing 36. I26 is associated with the brake and cover control mechanism in the housing 95. I34 is a centrifugal switch associated with the motor as previously described. The also comprises solenoids 48 48 is associated with the cover lock in the housing 36, and I04 is associated with the brake apparatus as previously described. It also includes the timer I33 and it further includes a start switch I31 and a stop switch I38.

The energization of the driving motor is controlled by a relay contactor switch I39. This switch includes an extra pair of contactors I 52 associated with a maintaining circuit.

The functions of the above electrical apparatus and the various circuits will now be described in connection with a complete operation of the ma- X chine.

tor is idle, and the cover ing bolt is then rotated into the clamping position, as shown in Figi' i, and the wing nut is turned down to securely hold the cover in place.

Movement of the clamping bolt to this position causes the cam 62 to rotate out of engagement with the lever 63 and permits the switch 66 to close. The push rod 94, being already in the lower latched position asshown in Fig. 5, when the cover is closed the rod I20 is elevated to the position of Fig. 6, the arms I21 and I26 move to the left permitting the switch I28 to close. The start button I31 is now depressed connecting terminals E1 and E2. This establishes a circuit from L1 through conductor 'I40, switch 66, conductor I4I, switch I31, conductor I42, conductor I43, timer terminals A1 to A2, conductor I44, conductor I45, timer motor I46, conductors I41 and I49, switch I26, conductors I49 and I50 to La. This energizes the timer motor and sets the timer in operation. Simultaneously a circuit is also established from terminal A2 by way of conductor I44, relay coil I5I, conductors I41 and I48, switch I26, conductors I49 and I50 to L3. This causes the contactor switch I39 to be closed energizing the drive motor 20 and also closing the maintaining contactor I52. As the motor begins to operate, the centrifugal switch I34 is opened, breaking circuit betweenterminals F1 and F2.

The closing of contactor I52 establishes the following maintaining circuit for the contactor switch I39. 'This is by way of conductor I40, switch 66, conductors I and I53, contactor I52, conductor I54, conductor I43, terminals A1 to A2 and thence through the timer motor and switch I26 to La, and simultaneously, through the coil I5I and switch I26 to Leas previously described. The maintaining circuit now being established, the start button I31 may be released.

When the time period for which the timer was set has elapsed, the timer returns to zero position and the contactor I55 of the timer switch returns to connect terminals A3 and A4, breaking connection between A1 and A2 This establishes the following circuit: from L1 by way of conductor I40, switch 66, conductor I51, terminals A3 to A4, conductor I58, conductor I59; coil of solenoid I04,.conductor I60, switch I26, conductors I49 to I50 to L3. A circuit is also established through the signal lamp I6I by way of conductors I62, I63 and I50 to L3. Illumination of the light designates the end of the extracting period.

Energization of the solenoid coil I04 causes the locking arm I02 to be elevated to the dashdot position of Fig. 6. This releases the latch I00 which frees the rod 94 and the stored energy in the brake spring 91 becomes effective to apply .the brake. This is performed under the control of the oil check IIO so that the braking effect is applied smoothly to cause the extractor basket to sto in a given time. Simultaneously, as the rod 94 moved upwardly and the brake was applied,'the upper end of this rod engaged the roller I30 on the arm I21, causing it to rotate clockwise, opening the switch I26. immediately opened the maintaining circuit for the solenoid coil I04. The upward movement of rod 94 is rather small, and finger 99 does not move above the upper end of latch I00. When solenoid I04 is deenergized arm I02 drops and engages shoulder I00a of latch I00. Subsequent opening of the cover depresses rod 94, latch I00 swings counterclockwise to locking po- This sition, and arm I02 drops to the position shown in F13. 5.

when the basket has come to rest. the mercury in the centrifugal switch drops back to the inner end connecting the terminals F1 and'Fz. The cover 25 may now be opened but, first of all. the clamping bolt 50 must be released and moved out of engagement to the position shown in full lines, Fig. 1.' This opens the switch 89 which, of course, prevents restarting of the motor. Now to unlock the cover so that it may be raised to the open position,-the stop button I39 is depressed. This establishes a circuit from L1 by way of conductor I40, conductor I65, terminals D1 and D2, conductor I66, solenoid coil 48, conductor I61, now closed switch I34, conductors I68 and I50 to Is. The coil 48 is energized as long as the stop button is held depressed and the energization of this coil rotates levers 46 and 44, see Fig. 4, which elevates the link 43, and rotates lever 42 and lock lever 38, removing the lock pin from the lock finger 40 so as to permit opening of the cover. It will be understood that when the clamping bolt was moved out of clamping position, the pin 60 was moved away from engagement with the lever 42 so that the lock lever 38 was free to be moved.

The sto switch I38 serves two purposes, one of which has Just been described, namely, to unlock the cover 25. The other purpose is to manually stop the extractor. In this case, during a running operation, when the stop button is depressed, a circuit is set up from L1 by way of conductor I40, conductor I65, terminals D1 to D3, solenoid coil I04, switch I26, conductors I49 and I50 to In. During this operation, of course,

the centrifugal switch I34 is open so that the circuit from terminal D2 is not energized. Energization of coil I04 initiates the same operations as previously'described for the time controlled stopping of the extractor. The stop button need only be held for an instant because immediately as the solenoid is energized and the latch I00 released, the switch I26 is opened and the stop button may be released. When the basket comes to rest and the centrifugal switch is closed, the stop button is again depressed to unlock the cover as before described.

Another way to terminate the operation is to depress the button I01 on the housing 95. This manually releases the latch I00 and permits application of the brake and opening of the motor circuit as previously explained in detail in connection with the operation of the timer and its effect on brake application.

When the cover is raised, the rod I20 is lowered to the positionshown in Fig. 5. In its lowering movement itengages the upper end of rod 94, pushing it downwardly until it is latched by I00. This resets the brake to off position ready for the next running period. Through its engagement with the roller I30, the switch I26 is maintained open until the cover is again closed. The inclusion of the arm I28 makes it necessary to completely close the cover before it is possible to energize the motor circuits. Also the brake must be completely off and latched.

It is apparent "from the above detailed description that I have provided mechanism whereby a cover for a curb member which houses. a rotatable work container cannot be opened while said work container is rotating; it is further apparent that even after said container has come to rest, a further clamp removing operation is required to permit unlatching 'means is in cover-securing functions of the several elements of the apparatus described.

, What I claim is:

1. A centrifugal extractor of the type described comprising a stationary curb, a basket rotatably mounted therein, electric motor means for rotating said basket, a cover for said basket mounted for opening and closing movement, a lock normally biased to hold said cover in closed position,

means operatively associated with said lock and responsive to the rotation of said basket for effecting release of said lock only when said basket is at rest, securing means in addition to said lock for holding said cover in closed position, an electric circuit for energizing said motor, and switch means in said circuit and operatively associated with, and responsive to changes in-position of said securing means whereby said motor-energization circuit is closed onlywhen said securing means is in cover-securing position.

2. A centrifugal extractor of the type described comprising a stationary curb, a basket rotatably mounted therein, electric motor means forrotating said basket, a cover for said basket mounted for Opening and closing movement, a lock normally biased to hold said cover in closed position, means operatively associated with said'lock and responsive to the rotation of said basket for effecting release of said look only when said basket is at rest, securing means in addition to said lock for holding said cover in closed position, an electric circuit for energizing said motor, switch means in said circuit and operatively associated with, and responsive to changes in position of said securing means whereby said motor-enerfor delayed control gization circuit is closed only when said securing carried by said securing means, and abutting said lock when said securing means is in cover-securing position, whereby release of said lock is then prevented. ,7

3. A centrifugal extractor of the type described comprising a stationary curb, a basketrotatably mounted therein, a cover for said basket mounted for opening and closing movement, a lock for holding said cover in closed position, an electric circuit, lock releasing means in said circuit energizable by passage of current through said circuit whereby said lock is released when said circuit is closed, means responsive to the rotation of said basket for maintaining said circuit in opencondition while said basket is in motion, electric motor means for rotating said basket, an

electric circuit for energizing said motor, a switchfor opening and closing said last named circuit, securing means in addition to said lock for maintaining said cover in associated with said securing means and with said switch for closing said switch only when said securing means is in cover securing position.

4. A centrifugal extractor of the type described comprising a stationary curb, a basket rotatably mounted therein, a cover for said basket mounted for opening and closing movement, a lock forholding said cover in closed position, an electric circuit, lock releasing means in said circuit energizable by passage of current through said circuit whereby said lock is. released when said cirposition, and means taining said cover in closed position, means associated with said securing means and with said switch forclosing said switch only when said securing means is in cover securing position, and

means associated with said securing means for preventing release of said look while said ing means is in cover-securing position.

- 5. A centrifugal extractor of the type described comprising a stationary curb, a basket rotatably mounted therein, a cover for said basket mounted for opening and closing movement, a lock for securholding said cover. in closed position, an electric circuit, lock releasing means in saldcircuit energizable by passage of current through said circuit whereby said lock is released when said circult is closed, centrifugal. switch means in said circuit, and responsive to rotation of said basket,

whereby said switch is opened during rotation of closed when said basket is at rest, electric motor means for rotating said basket, an electric circuit for energizing said motor, a second switch for opening and closing said last named circuit, securing means in addition to said lock for maintaining said cover in closed position, and means associated with said securing means and with said second switch for closing said second switch only when said securing means is in cover-securing position.

6. A centrifugal extractor of the type described comprising a stationary curb, a basket rotatably mounted therein, a cover for said basket mounted for opening and closing movement, a lock for holding said cover in closed position, an electric circuit, lock releasing means in said circuit energlzabl'e by passage of current through said circuit whereby said lock is releasedwhen said circult is closed, means responsive to rotation of said basket for closing said circuit only while said basket is at rest, a brake for said basket, means for applying said brake, a timer mechanism for energizing said brake applying means, electric motor means for rotating said basket, an electric circuit for energizing said motor, switch means for opening and closing said motor circuit, means operatively associated with said brake app ing means for opening said switch closed position, and means when said brake applying means is energized, securing means in addition to said lock for maintaining said cover in closed position, a second switch in said motor circuit, and means associated with said securing means and with said second switch for closing said second switch when said securing means is in cover-securing position. a

7. A centrifugal extractor of the type described comprising a stationary curb, a basket rotatably mounted therein, a cover for said basket mounted for opening and closing movement, a lock for closed position, an electric means in said circuit energizable by passage of current through said circuit whereby said lock is released when said circuit is closed, means responsive to rotation of said basket for closing said circuit only while said basket is at rest, a brake for said basket, means for timer mechanism for energizing said brake applying means, electric motor means for rotating said basket, an electric circuit means associated cuit energizable by passage of current through said circuit whereby said lock is released when said circuit is closed, means responsive to the rotation of said basket for maintaining said circuit in open condition while said basket is in motion, electric motor means for rotating said basket, an electric circuit for energizing said motor, a switch for opening and closing said last named circuit, securing means in addition to'said lock for maintaining said cover in closed position, means associated with said securing means and with said securing means for preventing release of said lock while said securing means is in cover-securing position.

8. A centrifugal extractor of the type described comprising a stationary curb, a basket rotatably mounted therein, a cover for said basket mounted for opening and closing movement, a 100k for holding said cover in closed position, an electric circuit, lock releasing means in said circuit, energizable by passage of current through said circuit whereby said lock is released when said circuit is closed, centrifugal switch means in said circuit and responsive to rotation of said basket whereby said centrifugal switch is opened during rotation of said basket and closed when said basket is at rest, a brake for said basket, means for applying said brake, a timer mechanism for ener izing said brake applying means, electric motor means for rotating said basket, an electric circuit for energizing said motor, a second switch means for opening and closing said motor circuit, means operatively associated with said brake applying means for opening said second switch when said brake applying means is energized, securing means in addition to said lock for maintaining said cover in closed position, a third switch in said motor circuit, and means associated with said securing means and with said third switch for closing said third switch when said securing means is in cover-securing position.

9. A centrifugal extractor of the type described comprising a stationary curb, a basket rotatably mounted therein, a cover for said basket mounted for opening and closing movement, a lock for holding, said cover in closed position, an electric circut, lock releasing means in said circuit energizable by passage of current through said circuit whereby said lock is released when said circuit is closed, means responsive to the rotation of said basket for maintaining said circuit in open condition while said basket is in motion, electric motor means for rotating said basket, an electric circuit for energizing said motor, a switch for opening and closing said last named circuit, securing means in addition to said lock for maintaining said cover in closed position, means associated with said securing means and with said switch for closing said switch only when said securing means is in cover-securing position, a brake for said basket, means for applying and releasing said brake, means for normally biasing said brake to applied position, latch means associated with said brake applying. means for preventing application of said brake, timer means for releasing said latch whereby brake application is initiated, and means for retarding application of full braking effect for a predetermined period after initiation of brake app cation.

10. A centrifugal extractor of the type described comprising a stationary curb, a basket rotatably mounted therein, a cover for said basket mounted for opening and closing movement, a lock for holding said cover in closed position, an electric circuit, lock releasing means in said cirswitch for closing said switch only when said securing means is in cover securing position, means associated with said securing means for preventing release of said lock while said securing means is in cover-securing position, a brake for said basket, means for applying and releasing said brake, means fornormally biasing said brake to applied position, latch means associated with said brake applying means for preventing application of said brake, timer means for releasing said latch whereby brake application is initiated, and means for retarding application of full braking effect for a predetermined period after initiation of brake application.

11. A centrifugal extractor of the type described comprising a stationary curb, a basket rotatably mounted therein, a cover for said basket mounted for opening and closing movement, a brake for said basket, means for applying said brake, a timer mechanism for initiating operation of said brake applying means, electric motor means for rotating said basket, an electric circuit for energizing said motor, said electric circuit including three switches in series, said motor being energized only when all three said switches are closed, means operatively associated with said timer and with the first said switch whereby said switch is opened after the expiration of the period for which the timer is set, means operatively associated with said brake applying means and with the second said switch whereby said second switch is opened when said brake applying means is energized by said timer as aforesaid, securing means for maintaining said cover in closed position, and means operatively associated with said securing means and with said third switch whereby said third switch is opened only when said securing means is detached from cover-securing position.

12. A centrifugal extractor of the type described comprising a stationary curb, a basket rotatably mounted therein, a cover for said basket mounted for opening and closing movement, a brake for said basket, means for applying said brake, a timer mechanism for initiating operation of said brake'applying means, electric motor means for rotating said basket, an electric circuit for energizing said motor, said electric circuit including three switches in series, said motor being energized only when all three said switches are closed, means operatively associated with said timer and with the first said switch whereby said switch is opened after the expiration of the period for which the timer is set, means operatively associated with said brake applying means and with the second said switch whereby said second switch is opened when said brake applying means is energized by said timer as aforesaid, securing means for maintaining said cover in closed position, means operatively associated with said securing means and with said third switch whereby said third switch is opened only when said securing means is detached from cover-securing position, a lock normally biased to hold said cover in closed position, a second electric circuit, lock releasing means in said second circuit energizable by passage of current through said second circuit whereby said lock is released when said second circuit is closed, and means responsive to rotation of said basket for closing said second circuit only while said basket is at rest.

13. A centrifugal extractor of the type described comprising a stationary curb, a basket rotatably mounted therein, a cover for said basket mounted for opening and closing movement, a brake for said basket, means for applying said brake, a timer mechanism for tion of said brake applying means, electric motor means for rotating said basket, an electric circuit for energizing said motor, said electric circuit including three switches in series, said motor being energized only when all three said switches are closed, means operatively associated with said timer and with the first said switch whereby said switch is opened after the expiration of the period initiating opera- 7 V for which the timer is set, means operatively associated with'said brake applying means and with the second said switch whereby said second switch is opened when said brake applying means is energized by said timer as aforesaid, securing means for maintaining said cover in closed position, means operatively associated with said securing means and with said third switch whereby said third switch is opened only when said securing means is detached from cover-securing position,a lock normally biased to holdsaid cover in closed position, a second electric circuit, lock releasing means in said second circuit energizable by passage of current through said second circuit whereby said lock is released when said second circuit is closed, a centrifugal switch in said second circuit and responsive to rotation of said basket whereby said centrifugal switch is opened during rotation of said basket and closed when said basket is at rest.

OSCAR W. JOHNSON. 

